Protecting means for electrical distribution systems.



G. A. BURNHAM. PROTECTING MEANS FOR ELEO'IBIGAL DISTRIBUTION SYSTEMS. APPLICATION FILED OCT. 28, 1911.

Patented Apr. 2, 1912.

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Inventor:

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G. A. BURNHAM.

PROTECTING MEANS FOR ELECTRICAL DISTRIBUTION SYSTEMS.

APPLIGATION FILED 00?. 2a, 1911.

1,022,355, Patented Apr. 2, 1912.

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UNITED STATES PATENT OFFICE.

GEORGE A. BURNHAM, 0F SAUGUS, MASSACHUSETTS, ASSIGNOR T0 S. B. CONDIT, JR., OF BOSTON, MASSACHUSETTS.

PROTECTING MEANS FOR ELECTRICAL DISTRIBUTION SYSTEMS.

To all whom it may concern:

Be it known that I, GEORGE A. BURNHAM, a citizen of the United States, residing at Saugus, in the county of Essex and State of Massachusetts, have invented an Improvement in Protecting Means for Electrical Distribution Systems, of which the following is a specification.

This invention relates to protecting means for electrical-distribution systems, whereby in case of an overload or abnormal condition of the circuit or fault which results in an overload, a switch will be operated to open the circuit. Heretofore overload switches have been controlled by tripping-magnets operated directly or indirectly by an overload; and lime-limit relays have been employed for controlling the operation of the tripping magnets so that all of the overload switches will not be operated and the entire Service discontinued.

My present invention involves a different principle of control for the tiippingiiiagnets, whereby the employment of time-limit relays is avoided, yet only one overload switch will be operated to open the circuit, thereby to maintain continuity of the service and at the same time afford adequate protection.

My present invention involves the employment at each sub-station of an overload switch and a trippingmagnet therefor, which is responsive to an overload, and means to prevent the tripping-magnet from operating to cause the over-load switch to open the circuit which is controlled by means located at the next sub-station, and which is responsive to an overload, but. more quickly responsive than the tripping-mag nets. Upon the occurrence of an overload all those trippingmagnets which ordinarily would respond are prevented from operating, with the exception of that one which is controlled by means located at a sub-station or place beyond the cause of the overload, whereupon that lrippingmagnet will respond to the overload and cause its overloadswitch to open the circuit.

In carrying out my invention lockingmeans are provided for the armalures of the tripping magnets adapted. when operated, to engage and hold said armaturcs in retracted positions. thereby to prevent the magnets from operating, and localmagncts are provided to operate said locking-means,

Specification of Letters Patent.

Application filed October 28, 1911.

Patented Apr. 2, 1912.

Serial No. 657,319.

the circuits of which extend to the next substations. Said local-magnet circuits are controlled by magnets connected in series relation with the tripping-magnets in the usual transformer circuits, but said controlling-magnets are constructed so as to respond more quickly to an overload than the tripping-magnets, as for instance they may be smaller than the tripping-magnets, so that upon the occurrence of an overload they will operate to cause the locking-means to engage the armatures of the tripping-magnets or means moved by said armatures, before the tripping-magnets will respond and thus prevent said tripping-magnets from responding. However, in case the lockingmeans of any of the tripping-magnets is not operated, then such tripping-magnet is free to respond and will do so if influenced by the overload, as for instance, when the controlling-magnet of any of the locking-means is beyond the cause of the overload, then its locking-means will not be operated, and the corresponding tripping-magnet is free to respond to the overload, and will do so and operate its overload-switch and open the circuit, and all the other tripping-magnets between said place and the source of supply will be prevented from operating, so that the continuity of the circuit between said place and the source of supply is maintained. Upon the cessation of the overload the controlling-means for the locking-means will be automatically restored to normal and the locking-means will be reset.

Figure 1 is a diagrammatical illustration of my invention, in connection with five substations, it being understood that any number of sub-stations may be employed. Fig. 2 is a more complete diagrammatical view of the instruments and circuits at one of the substations.

My invention is here illustrated by and in connection with an ordinary tri-phase system of electrical-distrihution wherein 10, 12 and let represent the main wires. and 15, ll? and ii feeder-wires leading therefrom at several substations marked 20, 21, 22, 23 and 24. .\t each substation an overload switch is provided, represented at 30, which is adapted to he released or otherwise controlled in any usual or suitable manner by a tripping-magnet 31. arranged in a transfiu'mer-rircuit and it will be understood that each phase or wire may be provided with a like overload-switch and tripping- Inagnet arranged in a transformer circuit, those of one phase only being shown in Fig. l, merely to simply illustrate the invention. In Fig. 2 the overload-switches of the three Wires or phases are connected together in the usual manner, and the actuator consists of a plunger 33, having a disk 34 secured to it, which is adapted to be engaged by the armatures 35 of several tripping-magnets, the operation of any one of which will cause the overload-switch to operate. The system thus briefly described is Well known in the art.

In Fig. 1, the armature of each trippingmagnet 31 has a projection 40, adapted to be engaged by a latch 41, pivoted, at 42, and having an extension43, bearing the armature of a local-magnet 44, and said latch is normally heldin its disengaged position, and the armature in its retracted position by a spring.

In Fig. 2 a projection 46, corresponding to the projection 40, is arranged on the plunger 33, and is adapted to be engaged by the pivoted latch 4.1, which is controlled by the local-magnet 14. hen the local-magnet is energized the latch will be caused to engage and lock the armature of the trippingmagnet, or the plunger, thereby to prevent the tripping-magnet or magnets from operating.

Each local-magnet -14 is arranged in a circuit to, and each circuit 50 extends from one to the next sub-station, so that a localrnagnet which is arranged at one sub-station may have its controlling-means at the next sub-station throughout the system. Said circuits 50 may be constructed as branches from a pilot-wire 51, or as separate local circuits, or otherwise, the source of supply for said circuits being immaterial, although preferably being independent of the dis tribution system.

The local-magnet circuits 50 are separately controlled by means at the sub-stations which responsive to an overload, but more quickly responsive than the tripping-magnets, and herein said local-magnet circuits have circuit-closers 55, which are normally open. and the movable members of which are connected with the armatures of controllinguuagnets 58, which are arranged in series relation with the tripping-magnets in the trausIorntor-circuits aid magnets may be made smaller than the tripping-magnets. so that they will be more quickly responsive, or they may be othcrwise ronstructml tor the accomplishment of this purpose.

Upon the occurrence of an overload. such for instance as may be caused by a shortcircuit at (it), or a fault, such as a ground at 61,, then. in such case, the trip iinganagl'iets and the controlliuganagnets at the sub-sta tions 20, 2t and 22 will be affected, but the contrclling-nlagnets will operate first, and lock the trippingmagnets at substations 20 and 21. The locking-means for the trippinginagnet at sub-station 22 is controlled by means located at substation 23, and will not be operated, for the reason that the controlling-means is located beyond the fault, hence the tripping-magnet at said substation 29 is free to operate and will do so, and cause its overload-switch to open the circuit.

Wherever the fault occurs it will be noted that the trippinganagnet nearest the cause, but between it and the source of supply will be operated, and all of the other trippingmagnets between said place and the source of supply will be prevented from operating, so that continuity of the service is maintained at those sub-stations not affected. Upon cessation of the overload the armatures on the controlling magnets will be restored to normal by springs attached thereto, and the lockingmeans for the tripping-magnets will be automatically reset by the springs attached to the pivoted latches 41. Thus restoring all of the operating means to normal automatically.

I claim 1. In an elect rical-distribution system including several sub-stations, an overloadswitch and tripping-magnet responsive to an overload, arranged at each sub-station, means to prevent operation of each trippingmagnet controlled by means located at the next sub-station and responsive to an overload, said controlling mcans being more quickly responsive than the tripping-magnets, whereby those tripping-magnets which ordinarily would respond to an overload are prevented from operating except the one whose controlling-means is located beyond the cause of the overload and which does not respond, substantially described.

2. I11 an electriraldistribution system in cluding several sub-stations, an overloadswitch and tripping-magnet responsive to an overload, arranged at each substation, locking-means to prevent operation of each trip ping-magnet, controlling means for each locking-means arranged at a sub station next the lockiiigiiieaiis which it controls, said controlling-incans being responsive to an overload but more quickly responsive than the lrippinganagncts, substantially as described.

3. In an electrical-distributi In system including several sub-statii'ins, an overloadswitch and trippingmagnct responsive to an overload, arranged at each substation, means to prevent operation of ea h tripping magnet. a controllirig-magnet For said incans which is located at a substation next the means which it. controls, and which is arranged in a transformer circuit. in series to lation with the tripping-magnet thereat, and which is more quickly responsive to an overload than the tripping-magnet, substantially as described.

4. In an electrical-distribution system including several sub-stations, an overloadswitch and tripping-magnet responsive to an overload, arranged at each sub-station, electro-magnetically operated means to prevent operation of each tripping-magnet, a local-circuit for each electromagnetically operated means extended to the next substation, a circuit-closer for each local-circuit at said next substation, and means responsive to an overload to operate said circuit-closer, said means being more quickly responsive than the tripping-magnet, substantially as described.

In an electrical-distribution system including several substations, an overload switch and tripping-magnet responsive to an overload, arranged at each sub-station, electro-magnetically operated means to prevent operation of each trippingmagnet, a lc(fal.cir('uit for each electro-magnetically operated means extended to the next substation and having its source of supply independent of the distribution-system, a cir' cnit-eloser for each local-circuit at said next sub-station, and means responsive to an overload to operate said circuit-closer, said means being more quickly responsive than the tripping-magnet, substantially as described.

(3. In an electrical-distribution system including several sub-stations, an overload switch and tripping-magnet responsive to an overload, arranged at each sub-station, a locking-device for the armature of each tripping-magnet, a local-magnet to operate each locking-device thereby to prevent operation of the trippinganagnet, a circuit for each loealanagnet. extended to the next sub-sta- Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

tion, and controlling-means at said sub-stations to operate said local-magnet circuits which are responsive to an overload but more quickly responsive than the trippingmagnets, substantially as described.

7. In an electrical-distribution system including several sub-stations, an overloadswitch and tripping-magnet responsive to an overload, arranged at each sub-station, means to prevent operation of each tripping-magnet controlled by means located at the next sub-station and responsive to an overload, said controlling-means being more quickly responsive than the tripping-magnets, and means to automatically restore said controlling-means upon cessation of the overload, thereby to permit automatic resetting of the means to prevent operation of the tripping-magnets, substantially as described.

8. In an electrical-distribution system including several sub-stations, an overloadswitch and tripping-magnet responsive to an overload, arranged at each sub-station, locking-means to prevent operation of each tripping-magnet, controlling-means for each locking-means arranged at a. sub-station next the locking-means which it controls, said contro-llingmeans being responsive to an overload but more quickly responsive than the tripping-magnets, and means to antomatically restore said controllirig-means upon cessation of the overload, thereby to permit automatic resetting of the lockingmeans, substantially as described.

In testimony whereof, I have signed my name to this specification, in the presence of two subscribing Witnesses.

GEORGE A, BURNHAM.

Witnesses B. J. Novas, H. B. DAVIS.

Washington, D. G. 

